It is well known to construct motor vehicle body doors, hoods, fenders, tailgates, trunks and deck lids by stamping an outer sheet metal panel and separately stamping an inner sheet metal reinforcing panel and then joining the two panels together by hemming a flange of the periphery of the outer panel over an adjacent edge of the inner panel to secure the panels together. Desirably, the outer panel is slightly larger than the inner panel to provide a border flange portion along the periphery of the outer panel which preferably has an upstanding lip which can be folded over the peripheral edge of the inner panel to define the hem flange which connects the two panels.
To provide a smooth and fair hem or fold line on contoured portions of a panel or at the corners of the sheet metal panels, the hemming apparatus must engage and hem the flange at a specific angle and along a specific path of travel to evenly and smoothly fold or hem the flange. Notably, the various panels of an automobile have different shapes and sizes with contoured portions or corners which require differently shaped hemming tools and hemming tools moving, on different planes or paths of motion to provide smooth and fair fold lines. Prior hemming devices have utilized a hem tool movable through a fixed path of motion to hem a particular corner of a particular panel. Hence, separate hemming devices must be specifically designed to form a particular portion of a particular panel thereby requiring a plurality of hemming devices to hem the comers or other contoured portions of various sheet metal panels.